Use of sand-filled geotextile tubes for sustainable coastal protection-case studies in Indian scenario

摘要

The geotextile tubes are widely used as reef structures, with their crest below the Mean Sea Level. The requirement of the beach width is the main criterion to decide crest level of the nearshore reef structure. For greater depth placement, stacked tubes may be one of the alternative solutions. In certain circumstances, the geotextile tubes are also used right at the eroding coastline. It is well known that tubes placed abutting to the eroding coastline get damaged at an early age. This has been experienced at Devbag in Maharashtra, Candolim in Goa and Shankarpur Coast in West Bengal. However, geotextile tubes placed at the eroding coast & covered with sand or rubble protection; enhance the life of the structure. In case of Beach Nourishment project, the unsegmented row of tubes placed below MSL is useful for many purposes. It acts as an offshore reef & helps in attenuating the wave energy directly attacking the coastline, it traps the sediments during the downrush and also acts as a barrier to hold the nourished sand. Recurring periodic expenditure of the beach nourishment also decreases after the beach stabilization within 2-3 years. Experiences with geotextile tubes for coastal protection works in India are described in the paper. Pros and cons of the geotextile tubes placement, crest level decision, significance of the protection of fabric from UV rays etc. are discussed in details with a few case studies.